Async: Question: async.parallel results order

Created on 2 Aug 2012 · 3Comments · Source: caolan/async

I understand that the async.parallel method run its task functions in parallel. However I am unsure about the order of the results.

Is the order of the results array dependant on:

When the parallel tasks callback. The first task to callback will have its results first in the final results array.

The order of the tasks were supplied in the async.parrallel method. The first task method will have its result first in the final results array.

Source

AaronAcerboni

Most helpful comment

This should be explicitly stated in the async docs.

davisjam on 22 Dec 2017

👍3

All 3 comments

Nevermind.

I can personally conclude that the 2nd instance is the correct one.

As clarified at the bottom of this example found in the README:

async.parallel([
    function(callback){
        setTimeout(function(){
            callback(null, 'one');
        }, 200);
    },
    function(callback){
        setTimeout(function(){
            callback(null, 'two');
        }, 100);
    },
],
// optional callback
function(err, results){
    // the results array will equal ['one','two'] even though
    // the second function had a shorter timeout.
});

AaronAcerboni on 2 Aug 2012

This should be explicitly stated in the async docs.

davisjam on 22 Dec 2017

👍3

Another help would be possibility for a way to pass a key to use in the array lookup in the final results array.